Pigment.



UNITED STATES PATENT ()FFICE.

CORNELIUS D. VREELAND, OF CHICAGO HEIGHTS, ILLINOIS.

PIGMENT.

SPECIFICATION forming part of Letters Patent No. 691,421, dated January21, 1902.

Application filed August 14, 1900. Serial No. 26,824- (No specimens.)

To all whom it may concern.-

Be it known that I, CORNELIUS D. VREE- LAND, a citizen of the UnitedStates, residing at Chicago Heights, in the county of Cook and State ofIllinois, have invented certain new and useful Improvements in theProduction of Materials for the Manufacture of Paints; and I do herebydeclare that the following is afull, clear,and exactdescription of thesame.

This invention utilizes the sludge derived as a waste product from themanufacture of sulfate of alumina from bauxite; and it comprises a newand useful paint material and a novel and efficient process of makingthe same.

As will be seen by reference to works treating of the material fromwhich alum is produced, (see, e. g., llftneral Industry of the UnitedStates, New York and London, 1899, Vol. 7, page 13, et seq.,) commercialbauxite contains, besides the aluminium, oxid and hydrate ofsilica,varying between certain limits, and iron oxid. The acid should,of course, contain these with sulfuric acid.

In the production of sulfate of alumina (frequently termed in commercepapermakers alum, fitter alum, concentrated alum, and alum cake) frombauxite by the acid process the bauxite is reduced to a more or lessbroken or pulverized condition and is then treated with dilute sulfuricacid, the resultant solution containing sulfate of alumina, while othercomponents of the bauxite are precipitated in the tank in which thebauxite is treated. The solution sulfate of alumina is then filtered,and there is deposited on the filter a further portion of material whichin no essential degree differs from the precipitate just mentioned,which, like it, I term sludge. This material from the filter may beadded to the other sludge which is deposited by precipitation in thetank. The sludge, by reason of the treatment of the bauxite withsulfuric acid, as stated, is distinctly acid, and for the purposes of myinvention this acid must be removed. This may be done by neutralizingthe acid constituents of the sludge, as hereinafter set forth. For thispurpose and also for a f urther purpose herein presently particularizedI add to the sludge barium oxid in suflicient quantity to practicallyneutralize the acid constituents aforesaid, the barium oxid combiningwith the acid to produce a sulfate of barium, the presence of which isnot only not injurious, but which is itself a valuable component of theproduct as a material for the manufacture of paint. In lieu of bariumoxid barium carbonate may be used with a like result, the weak carbonicacid of the carbonate being replaced by the stronger acid in the sludge,thus neutralizing the acid constituents of the latter by alikeproduction of barium sulfate. The proportion of barium oxid or of bariumcarbonate, as the case may be, to the quantity of sludge may vary withinwide limits. It should be sufficient to chemically neutralize all orsubstantially all the acid constituents of the sludge. The preferredresults are reached when the percentage of barium oxid or carbonate, asthe case may be, is very little above that required to neutralize theacid components of the sludge, as hereinbefore set forth. The sludgebeing thus brought to a neutral condition is then dried by any suitablemeans and exists in a powdered or comminuted form, which may be broughtto any desired uniformity of fineness by grinding or otherwise. Thematerial thus prepared and composed of the dry neutral sludge, combinedwith the barium oxid, (to produce barium sulfate as a constituent in theresultant compound as described,) provides a superior material for theproduction of paints, being forthat purpose ground in oil in the mannerusual with other paint materials. The paint may receive various colorsby the addition of a suitable pigment or pigments.

Dried neutral sludge produced in the manufacture of sulfate of aluminaby the acid process being set forth and claimed in my application SerialNo. 26,825, the same is not by itself claimed in this my presentapplication; but

WVhat I here claim as my invention is 1. As a new article ofmanufacture, a paint consisting of the sludge resulting from theproduction of sulfate of alumina from bauxite, dried and containingsulfate of barium in the intimate state of admixture produced byneutralizing the sulfuric acid of the sludge with oxid of barium, as setforth.

2. As a new article of manufacture a paint ICO composed of sludgeresulting from the probarium oxid the acid sludge derived from theduction of sulfate of alumina from bauxite production of sulfate ofalumina from bauxite [O by the acid process, neutralized by oxid of bythe acid process and drying the resultant barium, dried and reduced to asubstantially product, as set forth.

uniform degree of fineness, and ground in oil, CORNELIUS D. VREELAND. asset forth. \Vitnesses:

3. The process of producing a novel paint DANIEL S. DECKER,

material which consists in neutralziing with JAMES A. WHITNEY.

